A programmable display includes an interface with a control device, such as a programmable logic controller (PLC), and can display a state of the control device connected thereto via the interface and receive control instructions for the control device through a screen.
Such a programmable display allows its user to create screen data tailored to the units of a device to be controlled in order to display the state of the control device, in any manner by using screen creating software or the like. The user creates the screen data with components and drawing functions provided by the screen creating software.
Control screen data created by using the screen creating software is transferred from the screen creating software to the programmable display and stored in a nonvolatile memory of the programmable display. The programmable display operates with the control screen data stored in the nonvolatile memory.
To quicken actions when active, the programmable display uses a mechanism to load the control screen data stored in the nonvolatile memory into a volatile memory, in which input/output (I/O) is processed quickly, at startup of the programmable display, and to operate with the control screen data in the volatile memory after the startup.
When it is necessary to modify the screen data for reasons such as debugging of the screen data, the screen data is modified with the screen creating software, and the modified screen data is transferred to the nonvolatile memory of the programmable display. Because of the use of the mechanism described above, the action of the modified screen data is verified after the modified screen data is loaded into the volatile memory from the nonvolatile memory at startup of the programmable display.
In Patent Literature 1, a technique is disclosed that aims at debugging screen data without transferring the screen data to a programmable display.